Not many votes yet.. But I am surprised 6 yes and we have never seen a thread about this before. I have stock battery and I am like pushing really hard on the sides trying to do everything to get some weird noise to come out of it.. nothing.
Was really shocked you said this had a bad build quality too.. This has to be one of the more solid phones I have ever owned.. I don't feel like I have to baby the hell out of it just so something does not break (Looking at you Pre Plus).

Yes mine makes noises if I push in on the sides of the back cover. I think because the back cover is so flimsy and flexible, that is the reason why it creeks. Not a problem at all for me as I am using a VZW black hardshell case.
I also noticed that under normal handling, there is no problem at all with it creeking. I really have to squeeze pretty hard for it to make any noise.

Other than the back cover, this thing is built like a tank ! The tradeoff is worth it to me to have such a slim phone.

Mine did and I seem to have found a simple fix. Take a business card and cut it in half. Place over the battery and put the back cover back on. Phone stops creaking and even feels more solid. Mine wasn't that bad, but enough to annoy me.